1. Technical Field
The present invention relates to container liners. In particular, bulkheadless container liners designed for bulk transport of commodities by commercial transport vehicles, and liners with integral discharge funnels.
2. Background Art
Transportation of bulk commodities has been implemented using a variety of methods. A common method is to use a vehicle designed solely for bulk commodity transport. Vehicles of this type are available in both motor and rail transport forms. Examples of these vehicles are tank trucks used for bulk liquid transport, and rail cars with discharge funnels integrated into the floor of the container to allow unloading of granular commodities such as grain, sugar, coal, etc. A disadvantage to this type of transport solution is that because the vehicle is dedicated to a particular form of cargo, it creates a backhaul problem. A backhaul is the cargo carried by the vehicle on the return trip. Thus, the specialized nature of the vehicle reduces the probability that cargo will be carried in both directions of the trip and therefore reduces the productivity of the vehicle. In addition to the backhaul problem, the costs involved with cleaning and inspection of a vehicle designed for a particular cargo can increase the cost of shipping the cargo. For example, when the vehicle is used to carry food products, great care must be used to avoid contamination. For these reasons, it is desirable that a general purpose vehicle be provided the ability to carry a variety of cargo types.
Attempts have been made to use general purpose vehicles for transport of granular cargo. One known method has been to load the cargo into drums and then securing the drums inside the transport vehicles. While tending to reduce the exposure to air which may contaminate some cargo, this method has proven to be unsuitable for many food items due to the remaining possibility of contamination, and the desirability of avoiding metal contact with the food items. A further disadvantage to this method is the high cost of using drums for shipment. Not only are the drums themselves expensive, but filling, loading and unloading are expensive labor consuming activities. In addition, as the drums are loaded onto the vehicle, they must be restrained or else the movement of the vehicle may cause the drums to be damaged or overturned in transit. The expense of using drums is further increased due to the need to provide pallets to rest the drums on during transit. The drums must be disposed of or returned. In the first instance, the cost of the pallets become part of the cost of the cargo. In the second instance, the space taken by the pallets during the return trip reduces the amount of usable cargo space.
Bag, or pillow, containers have been developed which are sealed to prevent exposure to ambient air. To avoid movement of this type of container, restraining straps are used to hold the bag in place. In addition to the straps, bulkheads are often required to hold the ends of the bags in place when vehicle doors are opened. Bulkheads are typically expensive and time consuming to install. Further, these bags often require inner liners when transporting food products or other items requiring approval from government agencies such as the U.S. Food and Drug Administration.
Another known method is to secure a deformable liner to the inside walls of a cargo vehicle. The bottom of the liner rests on the floor of the vehicle. As the vehicle is loaded, the cargo presses the liner against the floor and walls of the vehicle. While useful for some types of cargo, this method is undesirable for food or other products which may be subject to contamination. To further protect the cargo, sealed bags have been developed to hold cargo in a clean, contained environment during shipping. These bags allow bulk commodities to be shipped using standard multipurpose cargo containers.
An attempt to provide a better solution to the issue of transportation of bulk cargo has been the development of sealable liners for use with general purpose transport containers. Typically, a flexible liner generally conforming to the internal shape of the container is secured to the inside of the container by straps and/or nailing the liner to convenient location within the container. The liner is held in place by a removable bulkhead to provide both for safety when loading or unloading, and for reducing the possibility of cargo loss if the liner should be damaged by movement when the container doors are opened.
The liner is typically unloaded by a variety of means. Pumps can be used to pull the cargo out of the liner. Likewise, a variety of mechanisms for lifting the front end of containers have been developed to allow the cargo to drain from a discharge port in the rear of the liner. The lifting approach has created some additional problems in that containers tend to be generally boxlike in shape. As a result, when granular cargo is unloaded, some of the cargo flows out the discharge port while some is trapped in the corners of the container liner. This, in turn, requires either extra labor to unload the remaining cargo or the lost value if the remaining trapped cargo is discarded.
The trapped cargo problem was addressed by the development of rigid angled corner units placed at the lower rear corners of the container. These corner units support the lower corners of the liner and act as a funnel, directing the cargo flow to the discharge port and away from the corners. Of course, the corner units have disadvantages similar to bulkheads in that the cost of the corner units, both in their construction cost and the cost to install and position them for each shipment, adds to the cargo cost.
Disadvantages associated with the prior art forms of bulk container liners are that they require extra labor to securely attach the liner to the proper locations within the container. Further, the attachment methods often include nailing or otherwise securing the liner to the inside of the container in a manner which causes some damage to the container itself. Likewise, the bulkheads and corner units increase the cost of the cargo due to the materials required to build the bulkhead and corner units as well as the labor to install them.
While addressing the basic desirability of using general purpose transport vehicles to move bulk granular cargo, the prior art has failed to provide a single bulk transport system which is inexpensive to manufacture, is sealed to minimize spillage, reduces contamination due to exposure to ambient air or air pockets, and can be used without straps, or other restraining devices, does not require bulkheads, and can be efficiently unloaded without corner units.